The shadow of the moon Mimas extends elegantly across Saturn's A and F rings.

As Saturn approaches its August 2009 equinox, the planet's moons cast shadows onto the rings. To learn more about this special time and to see a movie of a moon's shadow moving across the rings, see PIA11651. Two background stars are visible in the image. Mimas is not shown.

This view looks toward the sunlit side of the rings from about 62 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 7, 2009. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 101 degrees. Image scale is 6 kilometers (4 miles) per pixel.

The Cassini Equinox Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

Here I'm seeing the same effect on the shadow as in "Trumpeting the Equinox" , now at Mimas' shadow. This effect is changing the shadow's shape at the F Ring making it not perfectly elliptical. My idea is that there the F Ring is a bit higher ( thicker when seeing at the rings edge-on) changing the shadow's shape - especially at its center where it is at its brightest.